Abdominal multidetector CT in patients with varying body fat percentages: estimation of optimal contrast material dose.
OBJECTIVE
To determine if contrast material dose for abdominal multidetector computed tomography (CT), as determined by using body weight (BW), overestimates the amount of contrast material required in heavier patients.


METHODS
Institutional review committee approval and patients' written informed consent were obtained. CT images of the abdomen were obtained by using 2 mL per kilogram of BW of intravenous contrast material (300 mg/mL iodine) injected at 4 mL/sec in 161 consecutive patients (age range, 28-90 years; mean age, 63 years; 95 men, 66 women). CT scans were initiated 45 and 150 seconds after aortic enhancement increased by 50 HU. The patients were divided into low (37-54 kg) and high (55-75 kg) BW groups. The DeltaHU/I, where DeltaHU is change in CT number and I is iodine dose in grams, and adjusted maximum hepatic enhancement (DeltaHU/[I/kg]) were assessed for correlation with BW, body mass index (BMI), and body fat percentage (BFP) by using linear regression.


RESULTS
DeltaHU/I correlated (P < .001) inversely with BW in the aorta (r = -0.78) and liver (r = -0.80) and with BMI in the aorta (r = -0.59) and liver (r = -0.61) on portal venous phase images. Regression formula for the low BW group was DeltaHU/I = 4.1 - .044 x BW (P < .001) and for the high BW group was DeltaHU/I = 2.7 - .017 x BW (P < .001), suggesting that the amount of contrast material required with increased BW is less in the high BW group. Adjusted maximum hepatic enhancement directly correlated with BFP (r = 0.25, P < .01).


CONCLUSIONS
Excessive contrast material may inadvertently be given in heavier patients when the dose is determined by patient BW. Contrast material dose may need to be tailored in individual patients by using BFP.
Kondo
Hiroshi
H
Department of Radiology, Kizawa Memorial Hospital, Gifu, Japan.
Kanematsu
Masayuki
M
Goshima
Satoshi
S
Tomita
Yuhei
Y
Miyoshi
Toshiharu
T
Hatcho
Atsushi
A
Moriyama
Noriyuki
N
Onozuka
Minoru
M
Shiratori
Yoshimune
Y
Bae
Kyongtae T
KT
D000273:Adipose Tissue / Q000033:anatomy & histology*; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001027:Aortography; D015992:Body Mass Index; D001835:Body Weight; D003287:Contrast Media / Q000008:administration & dosage*; D005260:Female; D006801:Humans; D008099:Liver / Q000000981:diagnostic imaging; D008297:Male; D008875:Middle Aged; D011860:Radiography, Abdominal / Q000379:methods*; D014057:Tomography, X-Ray Computed / Q000379:methods*
D003287:Contrast Media